Electric connecting device

ABSTRACT

The invention relates to an electric connecting device, especially for arrangement between a steering wheel and a steering column switch module of a motor vehicle, comprising a stationary housing part ( 2 ) and a rotationable housing part ( 3 ) which t respectively include a connecting unit and enclose at least one spiral-shaped wound-up, flexible electric conductor ( 4 ) whose respective end is connected to the connecting unit and which is guided in a reverse-direction loop ( 5 ) inside the housing ( 1 ). The conductor ( 4 ) is associated with a forced guidance element ( 6 ) in a positive fit, engaging the peripheral side of the conductor ( 4 ) and resulting in a defined winding or unwinding of the conductor ( 4 ) during a rotational movement of the rotationable housing part ( 3 ).

The invention pertains to an electric connecting device, especially for arrangement between a steering wheel and a steering column switch module of a motor vehicle, comprising a stationary housing part and a rotatable housing part, which respectively include a connecting unit and enclose at least one spiral-shaped wound up flexible electric conductor whose end is connected to the connecting unit and which is guided in a reverse-direction loop inside the housing.

Connecting devices of this type are used, in particular, for producing an electrical connection between a power source and a gas-operated impact protection device of motor vehicles that is arranged in the steering wheel. In this case, a conductor arranged between the stationary housing part and the rotatable housing part is of such length that it can follow approximately three revolutions of the steering wheel in both directions. The flexible conductor widens outwardly when the steering wheel is turned in one direction from a central position until it contacts the stationary housing part and contracts inwardly when the steering wheel is turned in the other direction until it contacts the rotatable housing part. This uncontrolled widening and contracting of the conductor frequently leads to malfunctions.

The invention is based on the objective of developing an electric connecting device of the initially described type that always operates reliably when the rotational housing part is turned.

According to the invention, this objective is realized in that a forced guidance is assigned to the conductor in a positive fit wherein the forced guidance engages on the periphery of the conductor and causes the conductor to unwind and rewind in a defined fashion when the rotatable housing part is turned.

During this rotational movement, the conductor follows the forced guidance such that the conductor is wound and unwound in a controlled fashion when the rotatable housing part is turned. In addition, the forced guidance prevents the conductor from rubbing on the housing parts such that the noise produced by the conductor can be reduced.

In order to ensure a secure retention and guidance of the conductor, the forced guidance according to one embodiment of the invention comprises a toothing that is assigned to the rotatable housing part and engages into respective recesses arranged in the conductor. The forced guidance preferably also comprises a toothing that is assigned to the stationary housing part. The elasticity and prestress of the conductor that is guided inside the housing in the form of a reverse-direction loop cause the conductor to permanently adjoin the rotatable and stationary housing parts. This ensures that the toothing arranged on the respective housing parts engages into the recesses of the conductor. The toothing is preferably arranged on the peripheral surfaces of the opposing stationary housing part and/or the rotatable housing part.

The toothing is preferably realized integrally with the respectively assigned housing part. The toothing and the corresponding housing part are manufactured together by means of a plastic injection-molding process such that the toothing no longer must be subsequently fixed on the respective housing parts and the connecting device can be manufactured cost-efficiently.

In order to provide a forced guidance that reliably prevents any twisting or tilting of the conductor, the recesses are preferably arranged centrally in the conductor relative to its height.

In order to compensate for tolerances, the recesses preferably consist of oblong holes that form a perforation in the conductor, into which the nub-shaped teeth engage. The recesses can be produced by means of punching, and the design of the respective nub-shaped teeth ensures that the conductor is guided such that only little wear occurs.

In order to enable the connecting device to transmit relatively high currents, several conductors may be arranged in the housing in the form of layers that lie one on top of another. These conductors are respectively guided in a forced manner by the toothing engaged with the aligned recesses and provide a relatively large conductive cross section, for example, for powering the steering wheel heater of a motor vehicle.

It should be understood that the above-described characteristics, as well as the characteristics yet to be disclosed, are not only suitable for use in the respectively described combination, but also in different combinations. The scope of the present invention is defined by the claims only.

One embodiment of the invention is described in greater detail below with reference to the drawings. Shown are:

FIG. 1, a perspective representation of an electric connecting device according to the invention;

FIG. 2, an enlarged representation of the detail II according to FIG. 1, and

FIG. 3, a perspective representation of an alternative embodiment of the electric connecting device according to FIG. 1.

The electric connecting device comprises a housing 1 that essentially consists of a housing part 2 fixed in a (not-shown) steering column switch module and a housing part 3 that is rotatable relative to the aforementioned housing part and connected to a (not-shown) steering wheel. In this case, the steering column switch module with the housing part 2 fixed therein is arranged on the outer tube of a steering column. An electric conductor 4 is spirally wound up within the housing 1, wherein the electric conductor is of such length that the steering wheel can be turned by approximately three to four revolutions. The conductor 4 is guided within the housing 1 in the form of a reverse-direction loop 5 such that the conductor 4 can be realized with a relatively short length. A connecting unit for respectively contacting the conductor 4 with the on-board network via the steering column switch module and with a plug on the steering wheel is arranged outside the housing 1 on the end of the conductor 4 assigned to the rotatable housing part 3, as well as on the end of the conductor assigned to the stationary housing part 2.

A forced guidance 6 peripherally engages on the conductor 4 in order to ensure that the conductor 4 is wound and unwound in controlled fashion when the steering wheel is turned. The forced guidance 6 shown in FIGS. 1 and 2 comprises a nub-shaped toothing 7 assigned to the stationary housing part 2 and a corresponding toothing assigned to the rotatable housing part 3, wherein the respective toothing engages into recesses 8 in the form of oblong holes arranged in the conductor 4. The toothing 7 is realized integrally with the respectively assigned housing part 2, 3 and located approximately in the center of the conductor 4 relative to its height. Since the conductor 4 is guided in the form of a reverse-direction loop 5 and consequently has a certain elasticity or prestress, it peripherally adjoins the stationary housing part 2 as well as the housing part 3 that is rotatable relative thereto. This ensures that the respective toothing 7 engages into the recesses in the conductor 4.

According to FIG. 3, four conductors 4 are accommodated within the housing 1, wherein each conductor is guided in the form of a reverse-direction loop 5. The loops 5 are separated at intervals. The conductor 4 is wound and unwound on/from the rotatable housing part 3 (rotor) in a controlled fashion when the steering wheel is turned, namely due to the fact that the forced guidance 6 is realized in the form of a toothing 7 that is assigned to the rotatable housing part 3 and engages into the recesses 8 in the conductor 4 that are realized in the form of oblong holes. The toothing 7 is designed in the form of a trapezoid in order to securely guide the conductors 4. The guidance of the conductors 4 on the stationary housing part 2 is ensured by the pressing force that is generated with the aid of the reverse-direction loops 5 and presses the conductors 4 against the stationary housing part 2. 

1. An electric connecting device, especially for arrangement, between a steering wheel and a steering column switch module of a motor vehicle, comprising a stationary housing part (2) and a rotatable housing part (3) which respectively include a connecting unit and enclose at least one spiral-shaped, wound up flexible electric conductor (4) whose respective end is connected to the connecting unit and which is guided in a reverse-direction loop (5) inside the housing (1), characterized by the fact that a forced guidance (6) is assigned to the conductor (4) in a positive fit, engaging the peripheral side of the conductor (4) and resulting in a defined winding or unwinding of the conductor (4) during a rotational movement of the rotational housing part (3).
 2. The connecting device according to claim 1, characterized by the fact that the forced guidance (6) comprises a toothing (7) that is assigned to the rotatable housing part (3) and engages into the respective recesses (8) in the conductor (4).
 3. The connecting device according to claim 1 or 2, characterized by the fact that the forced guidance (6) comprises a toothing (7) that is assigned to the stationary housing part (2).
 4. The connecting device according to claim 2 or 3, characterized by the fact that the toothing (7) is respectively arranged on the peripheral surfaces of the opposing stationary housing part (2) and/or the rotatable housing part (3).
 5. The connecting device according to one of claims 2-4, characterized by the fact that the toothing (7) is realized integrally with the respectively assigned housing part (2, 3).
 6. The connecting device according to claim 2, characterized by the fact that the recesses (8) are approximately arranged centrally in the conductor (4) relative to its height.
 7. The connecting device according to one of claims 2-6, characterized by the fact that the recesses (8) are realized in the form of oblong holes that form a perforation in the conductor (4), into which the respective nub-shaped toothing (7) engages.
 8. The connecting device according to one of claims 1-7, characterized by the fact that several conductors (4) are arranged in the housing (1) in the form of layers that lie one on top of another. 